Arc chamber



Feb. 19, 1963 H. J. LINGAL 3,078,383

' ARC CHAMBER Filed April 29. 1960 I 8 6 Sheets-Sheet 1 Fig. I

Feb. 19, 1963 H. J. LINGAL 3,078,383

ARC CHAMBER Filed April 29. 1960 6 Sheets-Sheet 2 H. J. LINGAL ARCCHAMBER Feb. 19, 1963 6 Sheets-Sheet 3 Filed April 29. 1960 Feb, 19,1963 H. J. LINGAL 3,678,383

ARC CHAMBER Filed April 29. 1960 6 Sheets-Sheet '4 H. J. LlNGAL Feb. 19,1963 ARC CHAMBER 6 Sheets-Sheet 5 Filed April 29. 1960 Feb. 19., 1963.H. J. LINGAL 3,078,383

ARC CHAMBER Filed April 29. 1960 e Sheets-Sheet 6 United States Patent3,673,333 ARtC CHAMBER Harry J. lLingal, Pittsburgh, Pa, assignor toWestinghouse Electric (Corporation, East Pittsburgh, Pin, a corporationof Pennsylvania Filed Apr. 29, 1950, Ser. No. 25,762 9 Claims. (Q.313-452) The present invention relates generally to are chambers andmore particularly to a mechanism for drawing an arc in a pressurized arcchamber.

In a pressurized gas chamber for hypersonic wind tunnel testing or thelike, which uses an electric are for heating and expanding the gas, itis desirable upon start-up to develop the are gradually to its fulllength to avoid developing steep front mechanical shock waves whichmight cause rupture of the arc chamber walls. Depending upon the powerin the arc, the desirable time to develop the arc to its full length mayvary between one and several cycles. For this reason it is undesirableto start an arc by melting a short circuiting fuse wire connecting thepower electrodes.

The principal object of the present invention is to provide a new andimproved arc chamber.

Another object of the present invention is to provide an are drawingmechanism which starts the are by parting electrodes at a controlledrate of movement, thereby avoiding the development of severe shockwaves.

Another object of the present invention is to provide an arc drawingmechanism which transfers the arc to stationary electrodes upondevelopment of the proper length arc.

Another object of the present invention is to provide an are drawingmechanism wherein the actuating and controlling part of the mechanism islocated externally to the are chamber.

Further objects and advantages of the present invention will be readilyapparent from the following detailed description taken in conjunctionwith the drawing in which:

FIGURE 1 is an elevational view of an illustrative embodiment of thepresent invention;

FIG. 2 is a fragmentary assembly view, partly in section, of a portionof H6. 1;

FIG. 3 is an enlarged detailed view of a portion of FIG. 2;

P16. 4 is a fragmentary view, partly in section, talren along the linelVlV in FIG. 6;

FIG. 5 is an end elevational view of PEG. 4;

FIG. 6 is an elevational view of another portion of the presentinvention;

P16. 7 is an elevational view, partly in section, of still anotherportion of the present invention; and,

FIG. 8 is a sectional view taken along the line Vlll VIII in FIG. 7.

A hypersonic wind tunnel using an arc chamber as a generator dependsupon electrically increasing the internal energy of the emitted gas andutilizing Brownian movement to obtain directed kinetic energy for thedesired gas ve.ocity. Because of the necessarily tremendous powerinvolved, it is desirable to strike an electric are within the chamberand gradually increase its length so as to avoid excessive shock waveswhich might cause rupture of the arc chamber walls. The presentinvention provides apparatus for drawing an electric are between a pairof spaced stationary electrodes in the desirable manner.

For purposes of clarity, all like parts have been given the samereference characters throughout the several figures.

With reference to FIG. 1, the arc chamber 2 is illus trated mounted on astructural rack i. Admission of the gas to be heated in the arc chamber2 is accomplished by "ice the gas inlet pipe 6. Exit means for theheated gas at the desired velocity is provided by the vent 8, which ventis provided with an exhaust cooling jacket 10 with input and outputpipes 12 for a cooling medium.

Electrical connection to the upper electrode 30 (FIG. 2) is made by theupper connectors 14 encased in an insulation barrier 16. The lowerconnectors 18 provide electrical power to the lower electrode 32 (FIG.2). Both the upper connectors 14 and the lower connectors 18 alsoprovide conduit means for a cooling medium which flows in heat transferrelationship within the electrodes 30 and 32 to reduce the hot spottemperature of the electrode surfaces.

The actuating and controlling portion of the apparatus for drawing anelectrical are between the upper and lower electrode is secured to thearc chamber 2 and rack 4. An arc starter assembly 59 is slidably mountedwithin a gas tight container 20 and is actuated by the motion transfermechanism 3% which is driven by the driving apparatus 104). The gaspressure within the electrode container 20 and within the motiontransfer mechanism 3% is substantially equal to the pressure within thearc chamber 2 providing an additional advantage of the presentinvention. The actuating and controlling part of the apparatus islocated externally to the pressurized arc chamher 2. Therefore, thepressurized arc chamber 2 need not be opened between tests to insert astarting fuse wire or to adjust the length and speed of travel of thestarting electrode as is necessary with apparatus of the prior art.

REG. 2 is a fragmentary assembly view, partly in section, of the arcchamber 2. The present invention provides apparatus for drawing anelectric arc in the arc chamber 2; which arc chamber is claimed and morefully described in the copending patent application, Serial No. 19,528dated April 4, 1960, by Werner S. Emmerich and assigned to the sameassignee. As more fully described therein, the arc chamber 2 comprisesan upper and lower ring electrode 3% and 32, respectively, fixedlymounted and adapted to have an ionizing potential connected thereacrossby means of the upper connectors 14 and lower connectors 18respectively. Cooling coils 3d are embedded within the stationaryelectrodes to conduct heat away from the electrodes during operation ofthe arc chamber. A ceramic cylinder 36 encloses the volume between thestationary electrodes, forming an envelope which allows the admission ofincoming gases through slots 38. A magnetic field is establishedtransverse to the electric arc by means of the magnetic coils it? sothat the electric arc is forced along the ring electrodes 36 and 32 byprecession due to the action of the magnetic field.

The are starter assembly 50 is mounted within the arc starter guide 44and actuated by an electrical conducting rod 46 which in turn isconnected to on electrical insulating rod 48 and thence to a driving rodor gear rack 49 which extends through the bottom of the arc chamber 2,through the motion transfer mechanism 300 and into the sealed rodcontainer 2%. A gear rack or connecting rod 203 provides driving forceto the motion transfer mechanism 3% which in turn advances and retractsthe arc starter assembly St) to initiate and draw the arc to its properlength within the arc chamber 2.

Tracing the electrical circuit, the arc starter makes electricalconnection to the conducting rod 46 and hence to the arc starter guide.4 through a roller contact assembly 6h. The are starter guide 44 issecured to a lower manifold 4'7 which is at the same potential as thelower connectors 18.

Referring to FIG. 3, the arc starter 50 comprises a plurality of contactfingers 51, each pivotally mounted on individual pins 52. While twocontact fingers are shown for the purposes of illustration, it is to beunderstood that any suitable number of contact fingers may be used. Ashunt 53 electrically connects the contact finger 51 to a piston member54 and is secured at both ends by securing means such as set screws 55.A resilient member or spring 56 urges the contact finger 51 to make goodelectrical contact with the top and bottom electrodes 39 and 32,respectively, as the starter assembly St) advances and retracts betweenthe two stationary electrodes.

A ceramic disc or shield 57 is secured to the piston member 54 by meansof a formed receiving member 58. The ceramic insulator 57 assists thetransfer of the are between the upper electrode 3% and the contactfingers 51 to the upper electrode 319 and the lower electrode 32 bywiping the arc onto the lower electrode 32 as the arc starter assembly42 is retracted past the lower electrode when completing its cycle ofoperation. The ceramic shield 57 provides a heat insulating barrier forthe arc starter assembly 50. Thus, the high temperatures generatedwithin the arc chamber are contained within the desired envelope. Thepiston member 54 is secured to the conducting rod 46 which in turn makeselectrical contact with the roller contact assembly 69.

The roller contact assembly 60 comprises a plurality of electricalcontacts 61 Which are disposed to straddle the conducting rod 46 androll along the conducting rod 46 as it advances and retracts the arcstarter assembly. The contacts 61 are urged into electrical contact withthe conducting rod 46 by means of a compression member or spring 62,rigidly positioned at one end by means of a plate 63. The opposite endof the spring 62 abuts a bearing 64, separated by a washer 65 on eachside. The spring 62 applies force against a shoulder 66 urging thecontact 61 to make contact with the conducting rod 46. Roller bearings67 allow the contact '61 to rotate in the assembly 60 as the are starterassembly 42 advances and retracts.

Electrical connection from the roller contact assembly 60 to the arcstarter guide 44- is obtained through the roller bearings 67. Wheredesirable, additional electrical contact may be secured by use ofpigtails (not shown) which are secured to the rolling contact 61 at oneend by means of the mounting hole therein and the opposite end of thepigtails secured to the arc starter guide 44 in any suitable manner.

The driving mechanism 1% and latching mechanism 260 to advance andretract the arc starter assembly 51) is illustrated in FIGS. 4, and 6The driving means 100 comprises a pair of 'L-shaped brackets 1011 and102 welded together or secured by bolts or other suitable means to forma cradle. A wind-up shaft 104 is rotatably mounted in the bracket 102 bymeans of a bushing bearing 106. A driving shaft 168 is rotatably mountedin the end bracket 101 in a similar manner with the bushing bearing 110.The shafts 104 and 108 are independently rotatable and aligned on thesame axis by means of a dowel pin 112 integral with the wind-up shaft104 and a dowel opening 11-4 within the driving shaft 1&8 forming arunning fit therebetween allowing each shaft to rotate independently ofthe other.

The shafts 104 and 108 extend through a tension storage means or torsionspring 116 which is enclosed in a metal guard 118, in turn secured tothe bracket 102. The guard 118 contains the torsion spring 116 as asafety precaution should the torsion spring fatigue and rupture.

An index plate 120 secured by suitable means, such as welding, to thewind-up shaft 104 and adapted to rotate therewith engages a spring end122 of the torsion spring 116 by means of a pin 124. To hold the drivingmechanismin assembly at a desired preloading, a number of pins arelocated in the index plate 129. The opposite spring end 126 engages adriving plate 123 which is secured to the driving shaft 1%.

Initially, both the index plate 12:) and the driving plate 123 aresecured against rotation. The driving plate 123 is secured againstrotation by means hereinafter to be described. The index plate issecured by the holding latch or pawl 130 which is pivotally mounted bymeans of a pin 132 secured in an extension 134 secured to the endbracket 1G2. The pawl 130 is urged against the index plate 12s by aspring member 136 secured at one end to the pawl 13th and at theopposite end to the extension 134. The pawl 13d engages a slot in theindex plate 120 to prevent rotation of the index plate in the reversedirection.

H nce, by rotating the crank or operating handle 133 which is secured tothe Wind-up shaft 104, the torsion spring 116 provides a tension storageof energy, the magnitude of which, it will be shown, controls the speedwith which the arc starter assembly 59* advances and retracts betweenthe stationary electrodes in the arc chamoer 2. By torsionally windingup the spring 116 a potential driving force is available to act upon thedriving plate 1123 upon release of the drivingshaft 1%.

From FIG. 6, a lever arm 291 is rotatably mounted on the driving shaft1% and is secured from rotating in a counterclockwise direction by meansof the latching mechanism The power potential stored in the torsionspring 116 will be released when the lever arm 201 is uniatched.

The lever arm 261 has a slot 2&2 formed in the free end of the lever arm291 wherein is secured the opposite end of the gear rack or connectingrod 61 by means or" a bolt 2% and castle nut It is to be noted that theeffective length of the lever arm 221 is readily adjustable by slidingthe secured end of the gear rack 233 within the slot 2&2 therebyaltering and allowing selection of the limit of advance and retractionof the starting electrode within the arc chamber 2.

Securing the lever arm 221 from rotation is a latch 22! pivotallymounted at one end to the base plate 221 by means of a pin 222. Theopposite end of the latch 22% is urged into engagement with a shoulderof the lever arm 2611 by a compression spring 223 secured at one end bya pin 224 integral with an angle 225. The opposite end of thecompression spring 223 is secured to the latch 22% by means of a pin 226inserted in the latch. To release the lever arm 2111 a solenoidplungertype tripping relay 227 is mounted to the latching frame 221 andadapted, upon an electrical signal, to attract the link 228 withsufficient force to disengage the latch 229 from the shoulder of thelever arm 291. A latch guide 223 provides a track for the latch 22% toengage and disengage.

Since it is desirable that the arc starter assembly 50 advance andretract only once the compression spring 223 and the magnetic relay 227are so chosen that the latch 22% will reassume its initial position andreengage the lever arm 201 after a single rotation of the arm.

To cushion the shock of the lever arm 261 striking the latch 22%) uponcompletion of one rotation, a decelerator 236 is mounted on the baseplate 221. The clecelerator 239 comprises a lug 231 and a step 232rigidly secured together and pivotally mounted on a pin 233. The lug 231has a strike surface 239 adapted to receive a roller 207 mounted on thelever arm Ztlll by means of an integral pin 288. As the lever armcompletes one complete revolution, the roller 207 rolls along the strikesurface 239 of the lug 231 to decelerate the lever arm as it completesone revolution and reengages the latch 220. To adjust the decelerator236 a set bolt 234 and engaging nut 235, secured to a third leg 236,rigidly secured to the lug 231 and stop 232 and pivotally mounted on thepin 233, engages a stationary stop 237. A spring 238 secured at one endto the stationary stop 237 and at its opposite end to the third leg 236provides resilient means for urging the lug 231 to resist the "lever armrotation as the roller 2 97 rolls along the strike surface 239 of thelug The set screw 234 provides means for adjust ing the force with whichthe decelerator will oppose the lever arm as it completes onerevolution.

As the lever arm 261 makes a complete revolution it can be seen that thegear rack 293 will make a reciproeating motion which motion istransferred by the motion ransfer mechanism Silt? to the gear rack 49 ofthe arc starter assembly 59. The driving rack 293 engages a driving gear3% within the motion transfer mechanism 3th).

The motion transferring mechanism 3% comprises a driving gear 331 and adriven gear 3492 secured by Woodruff keys 3&3 to a shaft 364 which isrotatably mounted by thrust bearings 3% secured in a bushing 3%. Thebushing 3% is in turn threaded into the housing 3%.

It is to be recalled that the pressure within the housing 368 of themotion transfer mechanism 3% is equal to the pressure within the arcchamber. To contain the high pressure within the mechanism 3% a bushingpressure plate 310 is secured to the bushing 3% compressing a packingseal 312 and an Q-ring 314 of suitable material. Additional O-rings 316seal the bushing 3% to the housing 3%. Thus, it can be seen that thehigh pressure gas within the motion transfer mechanism is containedalong the bushing 366 and along the shaft 3% while at the same timeallowing connection between the internal and exte nal parts of themechanism.

A hanger guide 32d is adapted to pivot around the shaft 3% and forcesthe gear racl'; 2% into engagement with the driving gear 3531. Washers318 separate the hanger guide 320 from the driving gear 3M to allow thefree motion of the hanger guide. The hanger guide utilizes a pair ofrollers 32?; mounted therein to allow the gear rack 2b? to make itsreciprocating motion while engaging the driving gear Sill. The drivengear 3492 is rotated in the same motion. The driven gear engages thegear rack 49 of the are starter assembly 42 with the result that theconducting rod 46 advances and retracts during a rotation of the leverarm Ziil. A guide screw 139 secured by a nut 332 to the frame 30%engages a vertical slot extending along the gear rack 49 to position thegear rack so as to engage the driven gear From FIG. 7 it can be seenthat the opposite end of the gear rack 49 advances and retracts withinthe gas sealed container 245 which is also under the same pressure asthe arc chamber 2. Suitable sealing means such as O-rings 334 maintainthe gas tight seal between the motion transfer mechanism housing Ell-Sand the bottom side of the are chamber 2, to which it is secured bysuitable means such as bolts through the bolt holes 336.

It is a feature of the present invention that the actuating andcontrolling elements of the apparatus for drawing an electric arebetween the stationary ring electrodes are located externally to thepressurized arc chamher 2. The operating connection between elementslocated inside the pressurized chamber and those located outside thechamber is made through a gas tight seal. The scaling is notaccomplished by the use of a sliding seal with its attendantdisadvantages but by means of a compression seal of the motion transfermechanism housing 398, which seal is most efiicient.

In accordance with the present invention, upon startup of the arcchamber 2, the crank or operating handle 13% is rotated so as to wind-upthe tension storage means to a desired torsional load. The further thetension spring is Wound up, the faster the arc starter assembly 5d willbe advanced and retracted within the arc chamber 2. Upon release of thelever arm 201 by a suitable electric signal, the gear rack or connectingarm 2% will undergo an essentially reciprocating motion of one cycle.The hanger guide 32% compensates for any sidewise motion of the gearrack 20% and causes the gear rack 2% to engage the driving gear 301.Accordingly, the driven gear 362 transfers the motion of the gear rack2&3 to the gear rack 49 and the arc starter assembly will advance andretract within the arc chamber 2. It is to be noted that the limit ofadvance of the arc starter assembly 50 may be preset by adjusting theeifec-tive length of the lever arm 201. As the arc starter assembly 50reaches its maximum advancement and starts to retract, the electricpower to the upper connectors 14 and lower connectors 13 are energizedso that an ionizing potential appearing across the stationary electrodes30 and 3-2 will initially appear between the upper electrode 30 and thecontact fingers 51. As the arc starter assembly ss retracts the arebetween the upper electrode 36? and the contact finger 51 is graduallylengthened over a desirable preset time with a controlled rate ofmovement thereby avoiding development of severe shock waves.

Another feature of the present invention is that at the end of the arestarter assembly travel, the terminal of the arc will transfer to thebottom fixed electrode 32. The ceramic disc 57 will assist intransferring the are by wiping the arc to the bottom electrode. The arestarter '50 is retracted sufficiently to position the ceramic disc 57 toprotect the starter from heat damage.

Thus, it is readily apparent that the present invention has providedapparatus for drawing an electric are between a pair of spacedstationary electrodes in an arc chamber or the like which is subjectedto great pressure and temperature extremes. Conventional starting fusewires have been eliminated. The extent of travel and the speed ofadvance and retraction of the arc starter assembly .is controlled byexternal means. The pressurized arc chamber 2 need not be opened betweentests.

Although this invention has been described with a particular degree ofexactness for the purpose of illustration, it is to be understood thatall equivalents, alterations, and modifications within the spirit andscope of the invention are herein meant to be included. For instance,the present invention provides apparatus for drawing an electric arc inan arc chamber which is applicable to many uses besides hypersonic windtunnels. Such an arc chamber may be used for the magnetohydrodynamicgeneration of electric power. Additional applications include fixationand synthesis of various chemical compounds wherein extreme heatgeneration is required.

I claim as my invention? 1. Apparatus for drawing an electric arebetween a pair of spaced stationary electrodes within a pressurized arcchamber comprising, in combination: a starting electrode adapted totravel from one stationary electrode to the opposite stationaryelectrode and return transferring the arc therebetween; means forconnecting an ionizing potential across said electrodes; a rotatablymounted lever arm; means for rotating said lever arm at a predeterminedspeed; means responsive to an input signal for allowing the lever arm torotate one revolution; a link member pivotally mounted at the free endof said le ver arm; and motion transfer means connecting said linkmember to said starting electrode for transferring he motion of saidlink member to said starting electrode to advance and retract saidstarting electrode.

2. Apparatus for drawing an electric are between a pair of spacedstationary electrodes within .a pressurized arc chamber comprising, incombination: a starting electrode adapted to travel from one stationaryelectrode to the opposite stationary electrode and return transferringthe are therebet-ween; means for connecting an ionizing potential acrosssaid electrode; a rotatably mounted lever arm; means for rotating saidlever arm at a predetermined speed; means responsive to an input signalfor allowing the lever arm to rotate one revolution; a link memberpivotaily mounted at the free end of said lever arm; means for adjustingthe effective length of said lever arm; and motion transfer meansconnecting said link member to said starting electrode for transferringthe motion of said link member to said starting electrode to advance andretract said starting electrode.

3. Apparatus for drawing an electric are between a pair of spacedstationary electrodes within a pressurized epvaass are chambercomprising, in combination: a starting electrode adapted to travel fromone stationary electrode tothe opposite stationary electrode and returntransferring the arc therebetween; means for connecting an ionizingpotential across said electrode; a rotatably mounted lever arm; meansfor rotating said lever arm at a predetermined speed; saidlast-mentioned means comprising tension storage means and means forestablishing a predetermined amount of energy in said tension storagemeans; a lever arm rotatably mounted and connected to said tensionstorage means for receiving stored up energy urging rotation of said armupon release of said lever arm; release means responsive to an inputsignal for allowing the lever arm to rotate one revolution; a linkmember pivotally mounted at the free end of said lever arm; means foradjusting the effective length of said lever arm; and motion transfermeans connecting said link me iber to said starting electrode fortransferring the motion of said link member to said starting electrodeto advance and retract said starting electrode.

4. Apparatus for drawing an electric arc between a pair of spacedstationary electrodes within a pressurized a'rc chamber comprising, incombination; a starting electrode adapted to travel from one stationaryelectrode to the opposite stationary electrode and return transferringthe arc therebetween; means for connecting an ionizing potential acrosssaid electrodes; a rotatably mounted lever arm; means for rotating saidlever arm at a predetermined speed; said last-mentioned means comprisingan index plate and a driving plate rotatably mounted on first and secondindependently rotatable shafts respectively; a torsion spring secured atits opposite ends to the index plate and the driving plate respectivelyand peripherally spaced from said first and second shafts; said leverarm connected to rotate with said second shaft; means responsive to aninput signal for allowing the lever arm to rotate one revolution; a linkmember pivotally mounted at the free end of said lever arm; means foradjusting the eiiec tive length of said lever arm; and motion transfermeans connecting said link member to said starting electrode fortransferring the motion of said link member to said starting electrodeto advance and retract said starting electrode.

.5. Apparatus for drawing an electric are between a pair of spacedstationary electrodes within a pressurized arc chamber comprising, incombination; an arc starter assembly adapted to travel from onestationary electrode to the opposite stationary electrode and returntransferr'ing the arc therebetween; means for connecting an ionizingpotential between said opposite stationary electrode and said onestationary electrode; said are starter assembly including a driving rodand contact fingers adapted to be energized at the same potential assaid one stationary electrode and move between said stationaryelectrodes so as to develop an electric arc gradually to its full lengthacross said stationary electrodes; said are chamber having an auxiliarychamber through which said driving rod extends; a closure member securedto said auxiliary chamber in gas tight relationship therewith forcontaining said driving rod as it extends out of said auxiliary chamber;and means for advancing and retracting the driving rod a predetermineddistance and at a predetermined speed.

6. Apparatus for drawing an electric are between a pair of spacedstationary electrodes within a pressurized arc chamber comprising, incombination; an arc starter assembly adapted to travel from onestationary electrode to the opposite stationary electrode and returntransferring the arc therebetween; means for connecting an ionizingpotential between said opposite stationary electrode and said onestationary electrode; said are starter assembly including a driving rodand contact fingers adapted to be energized at the same potential assaid one stationary electrode and move between said stationaryelectrodes so as to develop an electric are gradually to its full lengthacross said stationary electrodes; said are chamber having an auxiliarychamber through which said driving rod extends; a closure member securedto said auxiliary chamher in gas tight relationship therewith forcontaining said driving rod as it extends out of said auxiliary chamber;motion transfer means including a driving gear and a driven gear; saiddriven gear being located within said auxiliary chamber and connected tosaid driving gear through a pressure tight seal; a .gear rack operablyconnected to said driving gear; and means for driving said gear rack ina reciprocating motion of two to three cycles duration with apredetermined length of travel and speed.

7. The apparatus of claim 6 wherein said are starter assembly includesan electrically conducting rod; a roller contact assembly including aplurality of roller contacts straddling said conducting rod and adaptedto roll along the surface of said rod making electrical contacttherewith; and means for-connecting said electricalroller contacts tosaid ionizing potential.

8. The apparatus of claim 6 in which said arc starter assembly consistsof at least one electrical contact finger pivotally mounted and adaptedto make electrical contact with the first and second stationaryelectrodes as the arc starter assembly advances and retracts; and a heatand electrical barrier secured to said are starter assembly trode andsaid one stationary electrode; said are chamher having an auxiliarychamber through which said starter assembly extends; a closure membersecured to said auxiliary chamber in gas tight relationship'therewithfor containing said starting assembly as it extends out of saidauxiliary chamber; and means 'for advancing and retracting thedriving.rod a predetermined distance and at a predetermined speed.

References *Cited in the file of this patent UNITED STATES PATENTS1,571,924 Kenyon Feb. 2, 1926 1,814,851 1931 1846,32 1 Kuntke Feb. 6,1934 2,607,024 Marwell et .al .d Aug. 1.2, 1952

1. APPARATUS FOR DRAWING AN ELECTRIC ARC BETWEEN A PAIR OF SPACEDSTATIONARY ELECTRODES WITHIN A PRESSURIZED ARC CHAMBER COMPRISING, INCOMBINATION: A STARTING ELECTRODE ADAPTED TO TRAVEL FROM ONE STATIONARYELECTRODE TO THE OPPOSITE STATIONARY ELECTRODE AND RETURN TRANSFERRINGTHE ARC THEREBETWEEN; MEANS FOR CONNECTING AN IONIZING POTENTIAL ACROSSSAID ELECTRODES; A ROTATABLY MOUNTED LEVER ARM; MEANS FOR ROTATING SAIDLEVER ARM AT A PREDETERMINED SPEED; MEANS RESPONSIVE TO AN INPUT SIGNALFOR ALLOWING THE LEVER ARM TO ROTATE ONE REVOLUTION; A LINK MEMBERPIVOTALLY MOUNTED AT THE FREE END OF SAID LEVER ARM; AND MOTION TRANSFERMEANS CONNECTING SAID LINK MEMBER TO SAID STARTING ELECTRODE FORTRANSFERRING HE MOTION OF SAID LINK MEMBER TO SAID STARTING ELECTRODE TOADVANCE AND RETRACT SAID STARTING ELECTRODE.